The objectives of these studies is to determine how healing takes place following various surgical-orthodontic procedures designed to increase or decrease facial height, determine stability after surgery, delineate what soft tissue is essential to maintain circulation to the mobilized maxillary bone fragments and teeth, and determine the effect of soft tissue flap design on circulation to bone and teeth by microangiographic and histologic studies. The histochemical, electromyographic and biomechanical changes in the muscles of mastication associated with surgical increase and decrease of facial height will be studied in 48 adult Rhesus monkeys.